Writing instrument



FIG. 1 is front elevational view;

FIG. 2 is a rear elevational view thereof;

FIG. 3 is a right side view, the left side view being a mirror image thereof;

FIG. 4 is a top plan view thereof;

FIG. 5 is a bottom plan view thereof; and,

FIG. 6 is a cross-sectional view taken along line 6—6 of FIG. 1. 

The ornamental design for a writing instrument, as shown and described. 